Nineteen north entry: Face and crosscut to right cleaned up. Limit of flame 10 feet inby last open crosscut. Flame did not reach face. Eighteen north entry: Face and crosscut to left cleaned up. Flame did not reach face. Room 21, 18 north: Cleaned up. Flame extended about 30 feet into room, but did not reach face. Room 20, 18 north: Face of room shot down. Top left rib shot misfired. Crosscut to left cleaned up, and loading machine parked out by crosscut switch. Flame extended 60 feet inside room, but did not reach face. Room 19, 18 north: Old fall at face of room. Room had been idle for 30 days. Room 18, 18 north: Left crosscut cut through to face of room 19. Cleaned up. Body found along left rib near face. Left rib of crosscut was shot to make connection with 19 room. Eight holes had been charged at the face of room 18. The top left rib shot had been exploded, resulting in a blown-out shot. Remaining holes were charged but not fired. Evidence of heat was present on the surfaces of all fuzes extending out of the holes. Flame extended to the face of the room. Four bodies, one of which probably was the shot firer, were found near the face. It was concluded that the top left rib shot was ignited by the explosion and blew out because the shots upon which it depended were not fired. A new crosscut was turned to the left near the face of room 18 and was in two cuts. Six holes had been charged at the face of this crosscut and the top left rib shot had been exploded, resulting in a blown-out shot. The remaining holes were charged but not fired. Evidence of heat was present on the surfaces of all fuzes extending out of the hole. It was concluded that the top left rib shot was ignited by the explosion and blew out because the shots upon which it depended were not fired. Room 17, 18 north: Eight holes at the face charged and stemmed. Fuzes were not ignited but showed evidence of heat on surfaces extending out of holes. Flame reached the face. Positive evidence of coal-dust stemming was found in the holes. Crosscut to the left cleaned up. Room 16, 18 north: Eight holes had been charged at the face. The top right rib hole and the third top hole from the right had exploded. The remaining holes were not fired but evidence of heat was present on the surface of all fuzes extending out of the holes. Flame extended to the face of the room. It was concluded that the two exploded charges were ignited by the flame of the explosion. crosscut cleaned up. Right Room 15, 18 north: Cleaned up. Room had not worked for about 6 weeks. Flame traversed this room. Room 14, 18 north: Face of room stopped previous to explosion. Crosscut turned to left near face, driven two cuts. Face of crosscut shot down. Coal fall appeared normal. Flame reached the face of the room and crosscut. Sixty feet back from the crosscut, another crosscut had been turned to the left to pick up No. 15 room. This crosscut had been driven almost its full length. The face was shot down and the coal fall appeared to be normal. A body, presumed to be the second shot firer, was found along the right rib in this crosscut. Flame extended about half way through the crosscut but did not reach the face. Room 13, 18 north Face of room, coal shot down. Coal fall appeared normal. Crosscut to right cleaned up. Flame extended to the face but did not extend outby the second crosscut from the entry. It is seen from the foregoing data, that blasting was not scheduled to be done in any of the rooms off 19 north, in the faces of 18 and 19 north entries, nor in rooms 15, 19, and 21 off 18 north. It appeared evident that the two shot firers started at opposite ends of the section to ignite shots and worked toward the center. It was, therefore, concluded that one shot firer ignited the shots in the face of room 20 and then proceeded to room 18 where a track crew was still working. At this juncture, the shot firer would have requested the track crew to go to the man-trip, but the explosion occurred before the men left the place and before the shot firer had an opportunity to ignite any of the shots in room 18. In the meantime, the other shot firer ignited the shots in room 13, then proceeded to room 14 and ignited the shots in the crosscut near the face, and then ignited the shots in the second crosscut from the face. The explosion must have occurred very soon after these shots were ignited, but before the shot firer had time to leave the crosscut. His body was found along the right rib of this crosscut. No evidence of movement of materials or other evidence of force could be found in rooms 13, 14, or 20, nor in any other working places in 18 or 19 north that would indicate that the explosion might have originated in one of these places. The information herein presented with reference to 18 and 19 north, and the workings thereof, leads to the conclusion that the explosion probably occurred before any of the ignited shots were detonated and that the explosion did not originate in any of these places. 20 and 21 north section, 1 west Room 5, 20 north: Face of room and crosscut to right shot down. Room 6, 20 north: Face shot down. Room 7, 20 north: Face of room shot down. Crosscut to left undercut but not drilled. Drill truck in room 70 feet from room switch. Room 8, 20 north: Face shot down. Room 9, 20 north: Face shot down. 20 north entry: Face shot down. 21 north entry: Face cleaned up. Room 9, 21 north: Caved at face prior to explosion. Room 8, 21 north Face shot down. Room 7, 21 north: Room face and crosscut to left shot down. Room 6, 21 north: Face of room partly loaded out. Room 5, 21 north: Face cleaned up. Room 4, 21 north: Face cleaned up. Room 3, 21 north: Face cleaned up. Clean-up car at face. From the foregoing data, it is known that blasting was not being done at the face of 21 north entry or in rooms 3, 4, 5, 6, and 9 off 21 north. Blasting was completed in 20 north entry, rooms 5, 6, 7, 8, and 9 off 20 north, and in rooms 7 and 8 off 21 north. The coal falls in all places appeared to be normal and there was no definite indication of forces in an outby direction between the faces and the first crosscuts of any of these places. The bodies of the shot firers were found with a number of other men at the man-trip, approximately 250 feet outby the face of 21 north. The entire 20 and 21 north sections 1 west were traversed by flame during the explosion. No evidence was found that would indicate that the explosion may have originated in the workings of 20 and 21 north 1 west. 20, 21, 22 north section, 4 west Room 36, 20 north: Face of room and crosscut on the left cleaned up. Room 39, 20 north: Face of room and crosscut to left clearned up. Room 41, 20 north: Cutting machine sumped in and half way across face. Controller off. Room 36, 22 north: Face of room cleaned up. Crosscut to left partly cleaned up. Loading machine back from face, nips off. Room 37, 22 north: Face cleaned up. Crosscut to left cut through and shot down. Room 38, 22 north Face and crosscut to left shot down. Three Room 39, 22 north Face of room shot down. Body of shot firer found 75 feet from face near last open crosscut. Shot firer's cap found at face. Crosscut to the left driven in three cuts. Six shots charged at face. bottom shots and top-right shot were not ignited, but indicated heat on fuzes projecting out of holes. Top-left shot and middle shot blown out. From the foregoing data it is known that blasting was not being done in any of the rooms off 20 north or in room 36 off 22 north. Blasting was completed in rooms 37 and 38, 22 north; the coal fall in these places appeared to be normal. In room 39 off 22 north, the face of the room was shot down and the coal fall appeared to be normal, but the last crosscut on the left which had been driven three cuts contained four unexploded charges and there was positive indication that the right top hole and the top center hole had been ignited and had blown out. Fuzes attached to the undetonated charges showed positive indications of heat on the outer surfaces. Three of the charges which were not detonated were probed during the investigation and it was found that they had been stemmed with coal dust in paper dummy bags. The body of the shot firer was found 75 feet from the face near the last open crosscut. It is customary for the two drillers who act as shot firers to ignite the shots as soon as possible after the men have left the working faces so that they will not delay the starting of the man-trip toward the shaft bottom. Accordingly, it is presumed that the two shot firers entered 38 room and one shots in the crosscut while the other ignited the shots in the face. shot firers then proceeded to room 37 and ignited the shots in the which he proceeded to the man-trip where his body was found. ignited the One of the face, after The other shot firer, after igniting the shots in room 38, proceeded to room 39 through one of the open crosscuts, but was caught by the explosion before he reached the crosscut where he was to fire the shots. A period of approximately 6 minutes & more would expire between the time the first shot was ignited and the time that shot would be detonated. Taking into consideration the amount of work to be done by the shot firers and the locations of their bodies as left by the explosion and the time required for the first shot to detonate after it was ignited, the investigators were of the opinion that the explosion occurred before any of the shots ignited in 37 and 38 rooms detonated. Moreover, no evidence of movemen of materials or other evidence of force could be found in those rooms or in any other places in 20 or 22 north that would indicate that the explosion may have originated in one of these places. It is concluded, therefore, that the explosion did not originate in 20, 21, or 22 north 4 west or the working places thereof. 1 west section First A. C. room 1 west: Face shot down. Second A. C. room 1 west: Face shot down. Crosscut to right cleaned up. 1 west entry: Face and crosscut to left shot down. (See Probable Point of Origin.) 2 west entry: Face shot down. First A. C. room 2 west: Face undercut and machine loaded on truck and moved back from face. Second A. C. room 2 west: Face shot down. Loading machine at face, nips off. The preceding data together with the fact that the bodies of the two shot firers were found at or near the man-trip on 1 west approximately 250 feet from the face indicated that the blasting operation was completed in this section, insofar as the ignition of the fuzes was concerned, when the explosion occurred. Five places were blasted in this section on the afternoon of the explosion. Assuming that at least 6 minutes had elapsed from the time the first shot was ignited to the time the first shot was detonated, it is believed that the shot firers had sufficient time to ignite all of the shots and travel to the man-trip loading station where their bodies were found, before the first shot exploded. All of the coal falls in the 1 west section, except the one at the face of 1 west, appeared to be normal and there was no evidence of blown-out shots. PROBABLE POINT OF ORIGIN The 1 west entry had been driven approximately 85 feet beyond the last open crosscuts to the right and left, and a crosscut had been turned to the left about 20 feet back from the face. (See sketch, appendix C.) A switch was in the process of being installed at this crosscut when the shift ended on the day of the explosion. A wooden spike box was upset and the spikes spilled on the floor, indicating forces outby. About 10 feet outby the spike box was a track wrench which had evidently been moved outby from the place where the trackman had been working. About 15 feet outby the track wrench, a tie had been lifted up and one end moved outby. A trackman's hammer was found near the last open crosscut to the left. It is believed that this hammer was moved outby from the point where the switch was being laid. Heavy deposits of plastic coke were present on the corner of the outby rib of the last open crosscut to the left. A bit box was upset at the bit station (see sketch, appendix C), with forces indicated outby. An oil barrel that was located at the bit station was blown outby for a distance of about 20 feet. Partially burned paper dummy bags, which were located at the bit station before the explosion, were found in the last open crosscuts to the right and left, indicating that when the forces from 1 west reached the junction of these crosscuts with 1 west, the explosion spread through openings in all directions from this point. There was no evidence of a blown-out shot at the face of 1 west. There was, however, some indication that would lead to the belief that the top rib shot was underburdened. The fact that the shot did not pull all of the coal at the right rib in a normal fashion suggests that an underburdened shot may have occurred. In any event, a blown-out shot of explosives that was stemmed with coal dust, or an underburdened shot of explosives could have ignited the coal dust. The dust cloud could have been raised by the shot which ignited the dust, or it could have been raised by preceding shots in the same working place or the adjacent crosscut. Permissible explosives will not produce dust explosions often, even if fired in the hazardous manner and under the hazardous dust conditions described in this report. But, when such hazardous practices and conditions are continued over a long period of time, the right combination of circumstances, such as a blownout or open shot and an ignitable dust cloud in the presence of such shot, will likely precipitate an explosion sooner or later. SUMMARY OF EVIDENCE Conditions observed in the mine following the explosion, together with information available from previous Federal coal-mine-inspection reports, provided ample evidence as to the point of origin and cause of the explosion. Facts based on this evidence are summarized as follows: 1. The mine was dry and dusty, and heavy deposits of fine coal dust were present on the roof, ribs, floor, and timbers of all active working sections in the mine. 2. Rock dust had not been applied in rooms, nor in entries for a considerable distance back from the working faces. 3. Methane in an appreciable amount was not found during recovery operations, and only a very small quantity of methane was found in air samples collected in poorly ventilated working faces during the investigation. No evidence was found to indicate that methane was involved in this explosion. 4. The explosion occurred at the end of the shift after all face operations had ceased, except for the blasting operations. Blasting was the only operation in progress capable of raising an ignitable dust cloud into the air at the time the explosion occurred. 5. Permissible explosives were being fired in a nonpermissible manner with caps and fuse, and coal dust was being used for stemming. 6. Major forces of the explosion radiated from the face workings of the 1 west entry in all directions toward open workings. 7. Flame from the explosion died away rapidly upon reaching rock-dusted zones in entries and upon reaching old abandoned workings in which falls covered up much of the coal dust which was left by the mining operations. 8. The only working place in which there was definite evidence of forces traveling outby in the area between the face and the last open crosscut was the face of 1 west entry. 9. There was definite evidence of radiation of forces to the north, south, and east at the junction of 1 west and the last open crosscuts to the right and left. CAUSE OF THE EXPLOSION Representatives of the United States Bureau of Mines who investigated the disaster are of the opinion that the explosion originated at the face of 1 west entry, that it was strictly a coal-dust explosion which was propagated by coal dust throughout four working sections of the mine, and that the coal dust was raised into the air and ignited by explosives fired in a dangerous and nonpermissible manner. LESSONS TO BE LEARNED FROM THE CONDITIONS AS THEY RELATE TO THE EXPLOSION 1. The outstanding lesson to be learned from this disaster is that mines which liberate little or no methane are not immune from widespread and tragic explosions if dry and dusty conditions exist therein and adequate measures are not taken to control the dust hazard. 2. This explosion has forcefully demonstrated the need to reevaluate the dustexplosion hazard. Up to the present time, it has not been customary for the coalmining industry, the Bureau of Mines, State Departments of Mines, or any other group dealing with mine safety matters to regard dry and dusty conditions in mines as constituting an imminent danger of such magnitude as to warrant the withdrawal of men, particularly if the mine does not liberate methane. If explosions of this type are to be prevented, it will be necessary to regard dry and dusty conditions in mines as being imminently dangerous in the future and to withdraw the men from the mine or portion thereof where such dangerous conditions exist, until appropriate measures have been taken to remedy such conditions. 3. The partial rock dusting of mines as a remedy for the coal-dust explosion hazard leads to a false sense of security. In this instance, the application of rock dust on haulage entries did not prevent the explosion from propagating from room to room through crosscuts. A study of the conditions revealed that this explosion propagated throughout four sections of the mine by traveling mainly through rooms and dying out as it reached the rock-dusted haulage roads and old abandoned areas. The spread of dust explosions from one working place to another will be prevented by means of rock dusting only when rock dust is applied in all working places up to and including the last open crosscuts. The application of rock dust along the haulage entries in this mine appears to have prevented the propagation of flame to the shaft bottom and probably saved the lives of 31 men. 4. Permissible explosives, charged and fired in a permissible manner, are safe explosives. Permissible explosives stemmed with coal dust and fired with fuse in a dependent sequence are dangerous. The maximum safety will be obtained, however, when all shots are fired in a permissible manner while all ine except the shot firers are out of the mine. 5. Evidence obtained during the recovery operations indicated that 44 me working in two sections of the mine, not affected by the flame or violence of the explosion, could have saved themselves if they would have had a knowledge of the principles of erecting barricades after explosions. RECOMMENDATIONS Recommendations concerning the safe operation of this mine were made in reports of previous Federal inspections, the last inspection having been made March 17-20, 1947. Recommendations in this report, therefore, are limited to conditions as they related to explosion hazards. RECOMMENDATIONS BASED ON THE FEDERAL MINE SAFETY CODE FOR BITUMINOUSCOAL AND LIGNITE MINES OF THE UNITED STATES ARTICLE IV. EXPLOSIVES AND BLASTING Sections 5a1 and 5a2.-Permissible explosives should be fired only with electric detonators of proper strength by means of permissible shot-firing units. Section 5a5.-Unless all shots are fired in series or in group series, an examination should be made of each shot, before it is fired, to see that it has a burden in all directions of at least 18 inches. If groups of shots are fired in series, an examination should be made of each series, before it is fired, to see that all holes in the series have a burden of at least 18 inches. Section 5a6.-Boreholes should be stemmed with at least 24 inches of incombustible material or at least one-half of the length of the hole should be stemmed if the hole is less than 4 feet in depth. Section 5a7.-Examinations for gas should be made immediately before and after each shot, if shots are fired while men other than the shot firers are in the mine. Section 5d.-All shots or series of shots should be fired immediately after charging, where shooting is done while men other than the shot firers are in the mine. ARTICLE V. VENTILATION AND MINE GASES Sections 3a and 3b.-The main intake air current should be divided into splits utilizing air crossings where needed, so as to ventilate all parts of the mine effectively. The number of men working on one split of air should not be more than 100 in order to conform to the requirements of the Illinois State Mining Law. Section 3c.-The quantity of air reaching the last open crosscut in any pair or set of entries should not be less than 6,000 cubic feet a minute. Section 6f.-Stoppings in crosscuts, between intake and return air courses, in entries other than room entries, should be built of solid, substantial incombustible material, such as concrete, concrete blocks, brick or tile. Section 10d.-Mine examiners should begin their examination in the first working place in their assigned territory not more than 4 hours before the shift for which they are examining enters the mine. Section 10j.-At least once during each working shift while the men are in the mine, the face bosses or other designated officials should examine all working places with a permissible flam safety lamp for methane noxious gases, and oxygen deficiency. ARTICLE VI. COAL AND ROCK DUST Section 1a.-Coal dust should not be permitted to accumulate on haulage roads or on the roadways of the working places. |